import _00GraphFuc as gf

#彼得松图不是平面图
V={'a','b','c','d''e','f','g','h','i','j'}
E={('a','b'),('b','c'),('c','d'),('d','e'),('e','a'),('a','f'),('b','g'),('c','h'),('d','i'),('e','j'),
    ('f','h'),('g','i'),('h','j'),('i','f'),('j','g')}
gf.drawgraph(E)
E=E-{('a','b'),('a','f'),('e','a')}
gf.drawgraph(E)
E=(E-{('b','c'),('b','g')})|{('c','g')}
E=(E-{('d','e'),('e','j')})|{('d','j')}
E=(E-{('f','h'),('i','f')})|{('h','i')}
gf.drawgraph(E)